Exploring spatio-temporal changes in the demersal and benthopelagic assemblages of the north-western Ionian Sea (central Mediterranean Sea)

Marine ecology progress series

V. Bandelj^3¹  R. Carlucci^1,2²  P. Ricci^1,2³ 

[1] CoNISMa, Piazzale Flaminio, 9 Roma, Italy^2;Department of Biology, University of Bari, Via Orabona, 4 - 70125 Bari, Italy^1;OGS (Istituto Nazionale di Oceanografia e di Geofisica Sperimentale), Oceanography Division, Via Beirut 2/4 (Ex-Sissa building), 34151 Trieste, Italy^3

关键词: Self-organising map;    SOM;    Demersal and benthopelagic assemblage;    Beta-diversity;    Indicator species;    North-western Ionian Sea;   

DOI  :  10.3354/meps12613

学科分类：海洋学与技术

来源: Inter-Research

【 摘 要 】

An exploration of the structure of demersal and benthopelagic assemblages in the north-western Ionian Sea was carried out by means of a set of statistical analyses. Self-organising map (SOM) and clustering methods applied to 183 taxa and their biomass (kg km-2) provided the classification of 1288 experimental hauls exploring the bathymetric range 10-800 m from 1995 to 2012. Six clusters were identified according to their similarities in species abundances (biomass), confirming the depth gradient as the main structuring agent. In order to identify key representative species in each cluster, the taxa were ranked by means of an indicator value index (IndVal) and the contribution of species to beta diversity (BD). Furthermore, the clusters were described by means of environmental and fishing characteristics. Particular habitat type, distance to canyon and fishing effort segregated the assemblages on the coastal shelf and slope. Temporal differences were detected in 2 bathyal groups, which were most likely affected by the 1990s environmental change in the deepwater circulation known as the Eastern Mediterranean Transient. The overall total BD in the study area was calculated as 0.79, with a temporal decrease observed at a rate of 0.7% yr-1. The approaches used are useful to identify and characterize the species aggregations inside complex faunal assemblages, without a priori assumptions about data distribution. These results can be a starting point for defining functional groups for Mediterranean food web modelling approaches, as well as for identifying indicator species to assess the environmental status in the context of the Marine Strategy Framework Directive.

【 授权许可】

Unknown